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bh=bNn3Gkj8eEfhoQRSqPAZgsCZ/OMlwZDfPyXZbMYK4G8=; b=ekvPw2f1JJti0PANIW1nPLl8K0sPvfrPexC0U7pyyrr9MM0Zd2WKOVrna0XHFkZ1nsoCva VqhLpcJCPlcVMF85WZtUE8c1xIj5aH+Cm+bfcBV1nh1HnskY4pl7STb/HXDhO4aW5dzUJ0 nTx528PGzuc/gfzmyr0Liaicyd0leOU= X-MC-Unique: fetYdvshP5yMK4nIpBvCuw-1 From: Paolo Bonzini To: qemu-devel@nongnu.org Subject: [PULL 027/115] hw/i386/vmport: Propagate IOPort read to vCPU EAX register Date: Thu, 11 Jun 2020 15:43:21 -0400 Message-Id: <20200611194449.31468-28-pbonzini@redhat.com> In-Reply-To: <20200611194449.31468-1-pbonzini@redhat.com> References: <20200611194449.31468-1-pbonzini@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=207.211.31.120; envelope-from=pbonzini@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/11 08:37:10 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Liran Alon , Nikita Leshenko Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @redhat.com) Content-Type: text/plain; charset="utf-8" From: Liran Alon vmport_ioport_read() returns the value that should propagate to vCPU EAX register when guest reads VMPort IOPort (i.e. By x86 IN instruction). However, because vmport_ioport_read() calls cpu_synchronize_state(), the returned value gets overridden by the value in QEMU vCPU EAX register. i.e. cpu->env.regs[R_EAX]. To fix this issue, change vmport_ioport_read() to explicitly override cpu->env.regs[R_EAX] with the value it wish to propagate to vCPU EAX register. Reviewed-by: Nikita Leshenko Signed-off-by: Liran Alon Message-Id: <20200312165431.82118-4-liran.alon@oracle.com> Signed-off-by: Paolo Bonzini --- hw/core/machine.c | 1 + hw/i386/vmport.c | 32 +++++++++++++++++++++++++++++--- 2 files changed, 30 insertions(+), 3 deletions(-) diff --git a/hw/core/machine.c b/hw/core/machine.c index bb3a7b18b1..83f0fe5c91 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -43,6 +43,7 @@ GlobalProperty hw_compat_4_2[] =3D { { "qxl", "revision", "4" }, { "qxl-vga", "revision", "4" }, { "fw_cfg", "acpi-mr-restore", "false" }, + { "vmport", "x-read-set-eax", "off" }, }; const size_t hw_compat_4_2_len =3D G_N_ELEMENTS(hw_compat_4_2); =20 diff --git a/hw/i386/vmport.c b/hw/i386/vmport.c index 5985167dcf..3bb420a245 100644 --- a/hw/i386/vmport.c +++ b/hw/i386/vmport.c @@ -43,6 +43,11 @@ #define VMPORT_ENTRIES 0x2c #define VMPORT_MAGIC 0x564D5868 =20 +/* Compatibility flags for migration */ +#define VMPORT_COMPAT_READ_SET_EAX_BIT 0 +#define VMPORT_COMPAT_READ_SET_EAX \ + (1 << VMPORT_COMPAT_READ_SET_EAX_BIT) + #define VMPORT(obj) OBJECT_CHECK(VMPortState, (obj), TYPE_VMPORT) =20 typedef struct VMPortState { @@ -51,6 +56,8 @@ typedef struct VMPortState { MemoryRegion io; VMPortReadFunc *func[VMPORT_ENTRIES]; void *opaque[VMPORT_ENTRIES]; + + uint32_t compat_flags; } VMPortState; =20 static VMPortState *port_state; @@ -80,17 +87,33 @@ static uint64_t vmport_ioport_read(void *opaque, hwaddr= addr, =20 eax =3D env->regs[R_EAX]; if (eax !=3D VMPORT_MAGIC) { - return eax; + goto out; } =20 command =3D env->regs[R_ECX]; trace_vmport_command(command); if (command >=3D VMPORT_ENTRIES || !s->func[command]) { qemu_log_mask(LOG_UNIMP, "vmport: unknown command %x\n", command); - return eax; + goto out; + } + + eax =3D s->func[command](s->opaque[command], addr); + +out: + /* + * The call above to cpu_synchronize_state() gets vCPU registers values + * to QEMU but also cause QEMU to write QEMU vCPU registers values to + * vCPU implementation (e.g. Accelerator such as KVM) just before + * resuming guest. + * + * Therefore, in order to make IOPort return value propagate to + * guest EAX, we need to explicitly update QEMU EAX register value. + */ + if (s->compat_flags & VMPORT_COMPAT_READ_SET_EAX) { + cpu->env.regs[R_EAX] =3D eax; } =20 - return s->func[command](s->opaque[command], addr); + return eax; } =20 static void vmport_ioport_write(void *opaque, hwaddr addr, @@ -142,6 +165,9 @@ static void vmport_realizefn(DeviceState *dev, Error **= errp) } =20 static Property vmport_properties[] =3D { + /* Used to enforce compatibility for migration */ + DEFINE_PROP_BIT("x-read-set-eax", VMPortState, compat_flags, + VMPORT_COMPAT_READ_SET_EAX_BIT, true), DEFINE_PROP_END_OF_LIST(), }; =20 --=20 2.26.2